The geomagnetic field was quiet to active on September 22 under the influence of a low speed stream associated with CH1031. The high latitude magnetometer at Andenes recorded quiet to major storm conditions.
Solar flux density measured at 20h UT on 2.8 GHz was 88.5 - decreasing 0.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 79.16). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.8). Three hour interval K indices: 43431022 (planetary), 32532111 (Boulder), 65233345 (Andenes).
The background x-ray flux is at the class B3 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 215) and in 7 active regions using 1K resolution (SN: 123) SDO/HMI images.
Region 12871 [S29E24]
produced a single C1.1 flare at 20:14 UT. The region still has 2 magnetic
delta structures. Then on September 23 at 04:32 a C5.4 flare and an M2.8
flare at 04:42 UT. An EIT wave was observed after the M class flare, it is
not yet known if there was an Earth directed CME as well.
Region 12872 [N17E17] developed further and has polarity intermixing.
C flares are possible.
Region 12873 [N25W33] displayed only minor changes and was quiet.
New region 12874 [S25W26] emerged on September 19 and was numbered 3
days later by SWPC as the region was decaying slowly.
New region 12875 [S31W35] emerged on September 20 and was finally
observed by SWPC 2 days later when the region was in slow decay.
Spotted regions not observed (or interpreted
differently) by SWPC:
S7089 [S26W50] decayed slowly and quietly.
New region S7092 [N28W39] emerged with several spots to the northwest
of AR 12873.
New region S7093 [N23W04] emerged with a tiny spot.
New region S7094 [N16E03] emerged with a tiny spot.
New region S7095 [N21E25] emerged with a tiny spot.
New region S7096 [S20E57] emerged with a tiny spot.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
September 20-22: No obviously Earth directed CMEs were observed in available LASCO imagery.
[Coronal hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A trans equatorial coronal hole (CH1032) was Earth facing on September 19-22. A northern hemisphere coronal hole (CH1033) will likely rotate across the central meridian on September 23-24.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is fair.
The geomagnetic field is expected to be quiet to active on September 23-27 due to effects from CH1032 and CH1033, occasional minor storm intervals are possible.
| Coronal holes (1) | Coronal mass ejection (2) | M and X class flares (3) |
1) Effects from a coronal hole
could reach Earth within the next 5 days. When the high speed
stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are red colored.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| S7080 | 2021.09.17 | N27W20 | |||||||||
| 12871 | 2021.09.18 | 7 | 25 | 13 | S28E25 | 0250 | DKO | DKC |
 |
 |
beta-gamma-delta location: S29E24 |
| S7082 | 2021.09.18 | N29W41 | |||||||||
| 12872 | 2021.09.19 2021.09.20 |
9 | 32 | 18 | N17E15 | 0070 | CAI | DAI |
 |
 |
beta-gamma location: N17E17 area: 0120 |
| 12873 | 2021.09.19 2021.09.20 |
5 | 14 | 8 | N24W35 | 0080 | DAO | DRO |
 |
 |
location: N25W33 |
| S7087 | 2021.09.19 | N15W42 | |||||||||
| 12874 | 2021.09.19 2021.09.22 |
2 | 9 | 4 | S25W26 | 0010 | HRX | CRO |
 |
 |
|
| S7089 | 2021.09.20 | 3 | 1 | S26W50 | 0005 | BXO |
 |
 |
|||
| 12875 | 2021.09.20 2021.09.22 |
3 | 7 | 4 | S32W34 | 0010 | BXO | CRO |
 |
 |
|
| S7091 | 2021.09.21 | N17E53 |
 |
||||||||
| S7092 | 2021.09.22 | 11 | 5 | N28W39 | 0040 | CRO |
 |
||||
| S7093 | 2021.09.22 | 1 | N23W04 | 0001 | AXX |
 |
|||||
| S7094 | 2021.09.22 | 1 | N16E03 | 0002 | AXX |
 |
|||||
| S7095 | 2021.09.22 | 1 | N21E25 | 0002 | AXX |
 |
|||||
| S7096 | 2021.09.22 | 1 | S20E57 | 0002 | AXX |
 |
|||||
| Total spot count: | 26 | 105 | 53 | ||||||||
| Sunspot number: | 76 | 215 | 123 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 49 | 132 | 80 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 83 | 118 | 98 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (cycle peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (cycle peak) |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2020.03 | 70.2 | 69.5 | 1.5 | 3.0 (+0.3) | 5.63 |
| 2020.04 | 69.5 | 70.0 | 5.4 | 3.6 (+0.6) | 5.32 |
| 2020.05 | 69.0 | 70.6 | 0.2 | 5.6 (+2.0) | 3.80 |
| 2020.06 | 69.5 | 71.7 | 5.8 | 7.9 (+2.3) | 3.75 |
| 2020.07 | 69.5 | 71.8 | 6.3 | 9.0 (+1.1) | 4.28 |
| 2020.08 | 71.6 | 73.4 | 7.6 | 9.5 (+0.5) | 5.68 |
| 2020.09 | 70.7 | 71.4 | 0.7 | 10.5 (+1.0) | 8.59 |
| 2020.10 | 74.6 | 74.2 | 14.6 | 11.9 (+1.4) | 6.13 |
| 2020.11 | 89.9 | 88.0 | 34.5 | 13.6 (+1.7) | 4.77 |
| 2020.12 | 86.9 | 84.2 | 23.1 | 15.3 (+1.7) | 4.72 |
| 2021.01 | 76.0 | 73.6 | 10.4 | 17.3 (+2.0) | 4.39 |
| 2021.02 | 74.3 | 72.4 | 8.3 | 19.1 (+1.8) | 9.50 |
| 2021.03 | 76.0 | 75.2 | 17.3 | (21.4 projected, +2.3) | 10.17 |
| 2021.04 | 75.9 | 76.4 | 24.5 | (25.0 projected, +3.6) | 8.40 |
| 2021.05 | 75.3 | 77.1 | 21.2 | (27.7 projected, +2.7) | 6.50 |
| 2021.06 | 79.4 | 81.8 | 25.3 | (30.9 projected, +3.2) | 5.52 |
| 2021.07 | 81.0 | 83.6 | 34.4 | (35.5 projected, +4.6) | 5.51 |
| 2021.08 | 77.7 | 79.7 | 22.4 | (40.2 projected, +4.7) | 6.19 |
| 2021.09 | 85.7 (1) | 36.5 (2A) / 49.8 (2B) / 53.7 (2C) | (45.9 projected, +5.7) | (6.8) | |
| 2021.10 | (50.3 projected, +4.4) | ||||
| 2021.11 | (54.9 projected, +4.6) | ||||
| 2021.12 | (60.7 projected, +5.8) | ||||
| 2022.01 | (64.3 projected, +3.6) | ||||
| 2022.02 | (69.1 projected, +4.8) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz
and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap indices.
4) Source: SIDC-SILSO.
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
